1. Field of the Invention
The invention relates to a specimen rack for specimen containers, such as test tubes, having M.times. N openings at its top to receive M.times. N specimen containers.
2. Prior Art
In the medical field, a great number of detection methods are known for discovering or identifying certain substances, one example being known as immunoassays.
A common feature of all these immunoassays is that to perform them, a more or less large number of method steps is needed to achieve buildup of the aforementioned complex, that includes the label, from the specimen taken from the patient in which the applicable substance is to be detected. This takes place in stages including, among other steps, addition of the labeled antibodies or antigens, elimination of excess substances, and so forth.
As a rule, such measurement techniques are not performed, on a commercial laboratory scale, "individually", that is, by successive processing of a single specimen container; instead, batch quantities of up to a 100 sample containers are typical. The problem consequently arises of how to make a large number of sample containers, as a rule test tubes, proceed quickly and reliably, without any change in their order, through these method steps. Between method steps, the specimen containers must be shifted repeatedly among the various pieces of equipment involved, and finally must be moved into the measuring instrument.
It is accordingly typical for the specimen containers, optionally after suitable pretreatment, used for performing this kind of measurement, which is composed of a plurality of method steps, to be kept in a rack while as many method steps as possible can be carried out. In the simplest case, such a rack comprises a plastic stand having, for instance, a matrix of 5.times.10 holes on its top, into which the specimen containers are inserted.
To avoid mixing up specimens, each test tube is generally individually written upon. This writing can for instance be done as long as the test tubes are not yet in the specimen rack. Sometimes, however, the specimens are already furnished in racks by the manufacturer, and then they must be individually removed from the rack, written upon, and replaced in the rack. The removal and replacement are labor-intensive.
Another problem is the addition of substances, or in other words the addition by pipette of patient samples, and--in the case of the immunoassay--the addition of the so-called labels, namely the radioactively or nonradioactively labeled antigens or antibodies. If the test tubes have the often-used dimensions of 12 mm in diameter and 75 mm in height, for example, then with conventional pipettes or dispensers it is not possible to pipette material with the required accuracy into the samples that stand vertically in the rack. This is primarily because the bottom of the test tubes cannot be seen during the pipetting, as long as the view is blocked by other specimen containers standing in the rack. The usual procedure is therefore to remove the test tubes individually for the pipetting, holding them obliquely with one hand, and guiding the pipette or dispenser with the other hand and performing the pipetting. After that, each test tube is replaced individually into the rack.